(a) Field of the Invention
This invention relates to a medical container with an electrolyte stored therein, and more specifically to a medical container which stores therein a body fluid replenisher to be administered through a peripheral vein or a central vein, such as an infusion solution, a dialysate for a circulatory system, such as an artificial kidney dialysate, or an electrolyte solution as a preserving solution for an organ or the like.
(b) Description of the Prior Art
Despite the inclusion of bicarbonate ions (HCO.sub.3.sup.-) at a certain specific concentration in the blood or tissue cells of the human body, either absolutely or practically no bicarbonate salt, carbonate salt or the like (hereinafter simply referred to as "bicarbonate" for the sake of brevity) is contained in an infusion solution for use in the treatment or the like of the human body, a dialysate or an organ (tissue) preserving solution, although certain particular electrolytes are contained therein.
For example, the concentration of bicarbonate ions in the plasma of the human body is generally around 24 mEq/l or so. When directly administering a bicarbonate into the body by infusion or when indirectly administering it by a blood dialysis or peritoneal dialysis, it is desired to add the bicarbonate in an amount such that the concentration of bicarbonate ions in the solution conforms with that of bicarbonate ions in the plasma. It is however to be noted that an infusion solution or the like is filled in a plastic-made medical container and is supplied to a hospital generally in a state completely sterilized by autoclave sterilization or the like. Bicarbonate ions are therefore caused to decompose substantially into carbon dioxide gas upon autoclave sterilization if a bicarbonate is added beforehand in the electrolyte in the container. Further, a bicarbonate, when filled as a diluted solution in a conventional plastic-made medical container, decomposes into carbon dioxide gas and is hence lost, even when the medical container is not subjected to autoclave sterilization.
Accordingly, no bicarbonate is used in infusion solutions, dialysates and the like and instead, a substance which can be yield bicarbonate ions in vivo is added. To maintain the concentration of bicarbonate ions constant in plasma or the like, an acetate, a lactate or the like is added as a substitute for a bicarbonate.
For example, a typical electrolyte-replenishing infusion solution contains Na.sup.+ at 20 to 50 mEq/l, K.sup.+ at about 20 mEq/l or so, Cl.sup.+ at 20 to 50 mEq/l, and CH.sub.3 CH(OH)COO.sup.+ or CH.sub.3 COO.sup.+ at 30 mEq/l. In addition, glucose, fructose, xylitol, sorbitol or the like is contained at 1 to 10 wt.%.
The acetate or lactate serves to yield bicarbonate ions in vivo, thereby replenishing same. It also maintain the infusion solution acidic so that stability is retained in a container. Accordingly, an acetate or lactate is widely used in infusion solutions these days.
Further, an infusion solution has conventionally been used in a closed system, namely, by filling it in a plastic-made container of variable volume which does not require a bottle plug piercing needle or the like. Such a container is generally subjected to autoclave sterilization after it is filled with the infusion solution. The infusion solution may however undergoes discoloration during the autoclave sterilization if it contains a saccharide and has a high pH value. To cope with this potential problem, an electrolyte-replenishing infusion solution is prepared with its pH value lowered as much as permissible.
On the other hand, a peritoneal dialysate has, for example, the following composition and properties.
Electrolyte concentrations (mEq/l):
______________________________________ Na.sup.+ 130 to 150 K.sup.+ as needed Ca.sup.2+ 1 to 6 Mg.sup.2+ 0 to 3 Cl.sup.- 90 to 135 CH.sub.3 CH(OH)COO.sup.- 30 to 45 Glucose (g/dl) 1 to 8 Osmotic pressure (mOsm/l) 300-680 pH about 5.5 ______________________________________
An acetate or lactate yields bicarbonate ions in vivo, and serves to replenish bicarbonate ions which are consumed during dialysis.
As organ-preserving solutions, Eurocollin's solution, Wisconsin's solution and the like have been proposed. The followings can be mentioned as illustrative components for the preparation of Eurocollin's solution:
______________________________________ K.sub.2 HPO.sub.4 7.40 g/l NaHCO.sub.3 0.84 g/l KH.sub.2 PO.sub.4 2.04 g/l KCl 1.12 g/l MgSO.sub.4 0.48 g/l Heparin 5,000 units/l Osmotic pressure 326 mOsm/kg ______________________________________
It has also been proposed to have organ-preserving solutions added beforehand with antibiotics, physiologically-active proteins (insulin, antiplatelet factors, antidiuretic hormones, and the like), saccharides (glucose, mannitol, and the like), vitamins (vitamin C, vitamin E, and the like), organic acids (lactic acid, citric acid, and the like), nucleic acid bases (adenosine triphosphate, and the like), antihypertensives (calcium antagonists, .beta.-adrenocaptive antagonists, angiotensin converting enzyme inhibitors, and the like), anticoagulants (heparin, and the like). Further, addition of drugs such as the phosphoric diester compounds disclosed in Japanese Patent Laid-Open No. 215801/1995 has also been proposed.
However, when an acetate or an organic acid such as citric acid are used in large amounts in such an electrolyte solution as practiced to date, the tendency of acidosis is observed in the body of a patient who cannot promptly decompose the acetate or the like, for example, in the body of a patient suffering from a liver problem. When the pH value of an infusion solution or the like is controlled as low as possible, a patient administered with the infusion solution is overdosed with the acid or acids and may develop a kidney problem, diarrhea, vomiting or the like. Such symptoms are often observed especially when the pH value is 5.0 or lower.
With a view to overcoming such problems of an electrolyte solution and also making it as close as possible in composition to a body fluid or a tissue cell fluid, it may be contemplated to add a bicarbonate. As described above, however, resulting bicarbonate ions are decomposed upon autoclave sterilization or even during storage, tend to be lost gradually as carbon dioxide gas.
With the foregoing in view, it was then proposed in Japanese Patent Laid-Open No. 105905/1994 to fill a bicarbonate solution in a compartment and then to enclose the compartment with a covering material having gas barrier property so that bicarbonate ions can be prevented from being lost as carbon dioxide gas. However, a bicarbonate in the form of an aqueous solution is mostly decomposed during autoclave sterilization, thereby failing to fully overcome the above-described problems.